Surgical tool assembly with compact firing assembly

ABSTRACT

A surgical stapling device includes a handle assembly, an elongate body extending distally from the handle assembly, and a tool assembly. The tool assembly is mounted onto the distal portion of the elongate body for articulation and includes a staple cartridge that supports a plurality of staples and pushers. An actuation sled is movable through the staple cartridge to eject staples from the staple cartridge and a clamp member is movable through the tool assembly to move the tool assembly from an open position to an approximated position and to advance the actuation sled through the staple cartridge to eject staples and transect tissue. In order to minimize the space for the firing assembly in the proximal portion of the tool assembly, the actuation sled and clamp member are supported in a nested relationship in a pre-actuated state of the tool assembly. The clamp member is subsequently moved to a position proximal of the actuation sled during a firing stroke of the stapling device.

BACKGROUND 1. Technical Description

The present disclosure is directed to an endoscopic surgical stapling device and, more particularly, to a surgical stapling device including a surgical tool assembly with a compact firing assembly.

2. Background of Related Art

Surgical stapling devices for endoscopic use include articulating tool assemblies. Linear endoscopic surgical stapling devices include a tool assembly having a pair of jaws, a drive member supporting a knife that is movable through the tool assembly, and an actuation sled configured to eject staples from a staple cartridge supported on one of the jaws. The tool assembly may also include a tissue stop that prevents tissue from being positioned within the tissue gap defined by the pair of jaws at a location proximally of the location of staples of the staple cartridge. The actuation sled is positioned distally of the drive member and the knife to facilitate formation of the staples in tissue prior to transection of the tissue.

Typically, the drive member includes clamping structure such as an I-beam to move the jaws of the tool assembly from an open position to a clamped position and to define a maximum tissue gap between the jaws of the tool assembly. In such devices, since the drive member is positioned proximally of the actuation sled and proximally of the tissue stop, the firing assembly of the tool assembly takes up a substantial amount of space; i.e., space on the tool assembly that could be used more efficiently for performing a stapling or cutting operation. In articulating surgical stapling devices, the space extending from the articulating axis or pivot point of the tool assembly to the tissue stop should be minimized to achieve greater access to the surgical site. This “dead space” restricts access to areas within a body cavity during an endoscopic surgical procedure.

It would desirable to minimize the space for the firing assembly within a tool assembly of a endoscopic surgical stapling device and to provide greater access to tissue within a body cavity during an endoscopic surgical procedure.

SUMMARY

In one aspect of the disclosure, a surgical stapling device includes an elongate body and a tool assembly supported on a distal portion of the elongate body. The tool assembly includes a cartridge assembly and an anvil assembly which are movable in relation to each other between spaced and approximated positions. The cartridge assembly includes a staple cartridge supporting a plurality of staples, a clamp member having a body supporting a knife, and an actuation sled including a cam member. In a pre-actuated state, the clamp member and the actuation sled are positioned in a nested relationship in which the knife of the clamp member is positioned distally of a proximal end of the cam member of the actuation sled. During at least a portion of a firing stroke of the surgical stapling device, the clamp member is movable proximally of the actuation sled to position the knife proximally of the cam member.

In embodiments, the cam member of the actuation sled includes first and second cam members interconnected by a bridge that defines a channel having an open proximal end.

In some embodiments, the clamp member includes a vertical strut, an upper beam, and a lower beam, wherein in the pre-actuated state of the stapling device, the vertical strut is positioned within a proximal portion of the channel.

In certain embodiments, the clamp member includes a nose and the bridge includes a cross member extending across a distal end of the channel.

In embodiments, the nose includes an engagement member that is positioned distally of the cross member in the pre-actuated state.

In some embodiments, during the firing stroke, the engagement member is moved to a position proximal of the cross member.

In certain embodiments, the engagement member includes a proximal ramped surface configured to pass under the cross member of the bridge and into the channel.

In embodiments, the engagement member includes a distal surface configured to engage the cross-member to translate distal movement of the clamp member to distal movement of the actuation sled when the engagement member is positioned proximally of the cross member.

In some embodiments, the clamp member includes at least one radial extension and the actuation sled defines a recess, wherein at least one radial extension is positioned within the recess in the pre-actuated state.

In certain embodiments, the at least one radial extension is positioned in a proximal portion of the recess in the pre-actuated state.

In embodiments, the cam member of the actuation sled includes first and second cam members interconnected by a bridge. The first and second cam members define a channel having an open proximal end and a cross-member at a distal end of the channel.

In some embodiments, the clamp member includes a vertical strut, an upper beam, and a lower beam, and in the pre-actuated state, the vertical strut is positioned within a proximal portion of the channel.

In certain embodiments, during a clamping stroke of the clamp member, the clamp member moves independently of the actuation sled such that the at least one radial extension moves from a proximal portion of the recess to a distal portion of the recess.

In embodiments, during the firing stroke, the at least one radial extension is moved from a position within the recess to a position proximal of the actuation sled.

In some embodiments, the recess is defined by an angled proximal end wall.

In certain embodiments, the at least one radial extension has a proximal ramped surface.

In embodiments, the at least one radial extension includes two radial extensions positioned on opposite sides of the clamp member.

In another aspect of the disclosure, a method of actuating a surgical stapling device includes advancing a clamp member within a tool assembly independently of an actuation sled to a clamped position to move the tool assembly from an open position to an approximated position, and advancing the clamp member through a firing stroke, wherein the firing stroke includes moving the clamp member and the actuation sled distally through a first advancement stage, moving the clamp member proximally independently of the actuation sled through a retraction stage, and moving the clamp member and the actuation sled distally through a second advancement stage to eject staples from the tool assembly.

In embodiments, moving the clamp member and the actuation sled distally through the first advancement stage includes moving the actuation sled distally past a stop member positioned to prevent proximal movement of the actuation sled.

In some embodiments, moving the clamp member proximally independently of the actuation sled includes moving a knife of the clamp member to a position proximally of cam surfaces of the actuation sled.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the presently disclosed stapling device including a tool assembly with a compact firing assembly are described herein below with reference to the drawings, wherein:

FIG. 1 is a side, perspective view of a surgical stapling device including one embodiment of the presently disclosed tool assembly in an open position;

FIG. 2 is a side, perspective of the tool assembly shown in FIG. 1 in an approximated position;

FIG. 3 is a side, perspective, exploded view of the tool assembly shown in FIG. 2;

FIG. 4 is an enlarged view of the indicated area of detail shown in FIG. 3;

FIG. 5 is an enlarged view of the indicated area of detail shown in FIG. 3;

FIG. 6 is a perspective view from the distal end of an actuation sled of the tool assembly shown in FIG. 5;

FIG. 7 is a side, perspective view of the clamp member, actuation sled and drive screw of the tool assembly shown in FIG. 3 with the clamping member and actuation sled in a retracted position;

FIG. 8 is a cross-sectional view taken along section line 8-8 of FIG. 7;

FIG. 9 is a cross-sectional view taken along section line 9-9 of FIG. 1;

FIG. 10 is an enlarged view of the indicated area of detail shown in FIG. 9;

FIG. 11 is a side, cross-sectional view of the tool assembly with the clamp member in a clamped position, the actuation sled in a retracted position, and the tool assembly in an approximated position;

FIG. 12 is an enlarged view of the indicated area of detail shown in FIG. 11;

FIG. 13 is a side, cross-sectional view of the tool assembly during the firing stroke as the clamp member and the actuation sled initially move through the tool assembly to eject staples from a cartridge assembly of the tool assembly;

FIG. 14 is a side, cross-sectional view of the tool assembly during the firing stroke as the clamp member is moved proximally in relation to the actuation sled to position a nose of the clamp member proximally of the actuation sled;

FIG. 15 a side, cross-sectional view of the tool assembly with the nose of the clamp member positioned proximally of and in engagement with the actuation sled;

FIG. 16 a side, cross-sectional view of the tool assembly with the nose of the clamp member positioned proximally of and in engagement with the actuation sled as the clamp member and the actuation sled are advanced through the firing stroke;

FIG. 17 is a side perspective view of an alternative embodiment of an actuation sled and clamp member with parts separated of the presently disclosed tool assembly;

FIG. 18 a side perspective view of the actuation sled and clamp member shown in FIG. 17 in an assembled condition;

FIG. 19 is a schematic side view of actuation sled and clamp member shown in FIG. 18 as the clamp member moves from a retracted position to a clamped position;

FIG. 20 is a schematic side view of the tool assembly shown in FIG. 19 during the firing stroke as the clamp member and the actuation sled move towards an advanced position;

FIG. 21 is a schematic view of the tool assembly shown in FIG. 20 as the clamp member moves proximally in relation to the actuation sled to a position proximally of the actuation sled;

FIG. 22 is a side, perspective view of a proximal portion of the cartridge assembly of the tool assembly shown in FIG. 21 during the firing stroke with the actuation sled engaged with stop tabs; and

FIG. 23 is a schematic view of the tool assembly shown in FIG. 21 during the firing stroke with the actuation sled engaged with tabs on the clamp member as the clamp member and actuation sled are advanced through the firing stroke.

DETAILED DESCRIPTION OF EMBODIMENTS

The presently disclosed surgical stapling device including a tool assembly with a compact firing assembly will now be described in detail with reference to the drawings in which like reference numerals designate identical or corresponding elements in each of the several views. In this description, the term “proximal” is used generally to refer to that portion of the device that is closer to a clinician, while the term “distal” is used generally to refer to that portion of the device that is farther from the clinician. In addition, the term “endoscopic” is used generally to refer to endoscopic, laparoscopic, arthroscopic, and any other surgical procedure performed through a small incision or a cannula inserted into a patient's body. Finally, the term clinician is used generally to refer to medical personnel including doctors, nurses, and support personnel.

The presently disclosed surgical stapling device includes a handle assembly, an elongate body extending distally from the handle assembly, and a tool assembly which is supported on a distal portion of the elongate body and has a compact firing assembly as compared to known surgical stapling devices. In embodiments, the tool assembly is mounted onto the distal portion of the elongate body for articulation and includes a staple cartridge that supports a plurality of staples and pushers, an actuation sled that is movable through the staple cartridge to eject staples from the staple cartridge, and a drive or clamp member. The clamp member is movable through the tool assembly to move the tool assembly from an open position to an approximated position and to advance the actuation sled through the staple cartridge to eject staples and cut tissue. In order to minimize the space for the firing assembly in the proximal portion of the tool assembly, the actuation sled and clamp member are supported in a nested relationship.

FIG. 1 illustrates a surgical stapling device 10 including a handle assembly 12, an elongate body 14, and an exemplary embodiment of the presently disclosed tool assembly 100. Although not described in detail herein, the tool assembly 100 can form part of a reload assembly 16 that is releasable from elongate body 14 as is known in the art. Alternately, the tool assembly 100 can be fixedly secured to a distal portion of the elongate body 14. The handle assembly 12 includes a hand grip 18, a plurality of actuator buttons 20, and a rotation knob 22. The rotation knob 22 facilitates rotation of the elongate body 14 and the reload 100 in relation to the handle assembly 12 as is known in the art. The actuator buttons 20 control operation of the various functions of the stapling device 10 including approximation, firing and cutting. The reload can be configured for use with a robotic surgical system. Although the stapling device 10 is illustrated as an electrically powered stapling device, it is envisioned that the presently disclosed tool assembly 100 would also be suitable for use with a manually powered surgical stapling device. U.S. Pat. No. 9,055,943 (“'943 patent”), hereby incorporated by reference herein in its entirety, discloses a surgical stapling device having a powered hand piece, an adapter, and a tool assembly that is releasably coupled to the adapter.

Referring to FIGS. 2 and 3, the tool assembly 100 includes an anvil 102, and a cartridge assembly 104. The cartridge assembly 104 includes a staple cartridge 106 that supports a plurality of staples 108 and pushers 110, a cartridge channel 112 defining a bottom surface 112 a, a staple cartridge support plate 114, a drive screw 116, a clamp member 118, and an actuation sled 120. The support plate 114 includes a resilient protrusion, e.g., a resilient lance 114 a (FIG. 4), that defines a stop surface for the actuation sled 120 as described in further detail below. Alternatively other protrusion configurations are envisioned. The staple cartridge 106 defines a central knife slot 140 and is attached within the support plate 114 by a snap-fit or other connection. The support plate 114 and staple cartridge 106 assembly are attached to the cartridge channel 112 also by a snap-fit connection. Alternately, other techniques for securing these components together may be used. The staple cartridge 106 includes a tissue contact surface 124 that defines a plurality of rows of laterally spaced staple retention slots 124 a configured as holes in the tissue contacting surface 124. Each slot 124 a receives one of the staples 108 and a respective pusher 110. The staple cartridge 106 also defines a plurality of longitudinal cam slots (not shown) which accommodate the staple pushers 110 and are open on an end opposite to the tissue-contacting surface 124 to facilitate passage of the actuation sled 120.

The anvil assembly 102 is pivotally coupled to the cartridge assembly 104 about pivot members 122 that extend through openings 125 defined in a proximal portion of the anvil assembly 102 and openings 127 defined in a proximal portion of the cartridge assembly 106. The anvil assembly 102 is pivotal in relation to the cartridge assembly 106 to transition the tool assembly 100 between open (FIG. 1) and approximated (FIG. 2) positions. The anvil assembly 102 includes a tissue contact surface 102 a (FIG. 9) that defines a plurality of staple deforming depressions (not shown) as is known in the art. The anvil assembly 102 includes an abutment surface 128 (FIG. 9) and a tissue stop 130. The abutment surface 128 is positioned to be engaged by the clamp member 118 to facilitate movement of the tool assembly 100 from the open position to the approximated position. In embodiments, the tissue stop 130 includes a pair of downwardly extending wings 130 a positioned on opposite sides of the tissue contact surface 102 a of the anvil assembly 102. The wings 130 a extend below the tissue contact surface 124 of the staple cartridge 106 when the tool assembly 100 is in the open position and have a distal tissue engaging surface 130 b. The tissue stop 130 prevents tissue from passing into the tool assembly 100 between the anvil and cartridge assemblies 102, 104 beyond the tissue stop 130 to prevent tissue that cannot be stapled from being cut.

Referring also to FIGS. 5 and 6, the clamp member 118 includes a base 142, a vertical strut 144, an upper beam 146, and a lower beam 148. The vertical strut 144 has a first end secured to the base 142 and a second end secured to the upper beam 146. Alternately, the base, upper beam and vertical strut can be integrally formed as a unit. In embodiments, the base 142 defines a threaded bore 150 that rotatably receives the drive screw 116 (FIG. 3). The drive screw 116 is threaded and is rotatable within the threaded bore 150 of the clamp member 118 to translate the rotational movement of the drive screw 116 into longitudinal movement of the clamp member 118.

The vertical strut 144 includes a distal surface that defines a knife 152 that is positioned between the upper and lower beams 146, 148. The upper beam 146 is positioned to engage the abutment surface 128 of the anvil assembly 102 such that movement of the clamp member 118 from a retracted position to a clamped position moves the tool assembly 100 from the open position (FIG. 9) to the approximated position (FIG. 11). The upper beam 146 is also positioned to translate through a channel 160 (FIG. 9) defined in the anvil assembly 102 and the lower beam 148 is positioned to translate along the bottom surface 112 a of the cartridge channel 112 to define a maximum tissue gap between the tissue contact surfaces 102 a, 124 of the anvil assembly 102 and the staple cartridge 106.

The clamp member 118 also includes a nose 164 that extends distally from a surface of the base 142 that is spaced from the lower flange 148. The nose 164 supports an engagement member 166 that includes a proximal ramped surface 166 a and a distal surface 166 b that is configured to engage and advance the actuation sled 120.

The actuation sled 120 includes a pair of spaced cam members 170 a, 170 b. Each cam member 170 a, 170 b is positioned to translate through a respective longitudinal cam slot (not shown) of the staple cartridge 106 and interact with the pushers 110 (FIG. 3) to eject staples 108 from the staple cartridge 106 as is known in the art. In embodiments, each of the cam members 170 a, 170 b includes two spaced cam surfaces 174, 176 that sequentially engage the pushers 110 (FIG. 3) as the actuation sled 120 translates through the staple cartridge 106 to lift the pushers 110 within the staple retention slots 124 a of the staple cartridge 106 and eject the staples 108 from the staple retention slots 124 a of the staple cartridge 106. The angle of the cam surfaces 174, 176 may vary along the length of the cam surfaces 174, 176 to better control movement of the pushers 108 through the staple retention slots 124 a and provide better staple formation. For example, the cam surfaces 174, 176 may have a distal portion 180 and a proximal portion 182 wherein the proximal portion 182 is steeper than the distal portion 180.

The cam members 170 a, 170 b are connected together by a bridge 184 that defines a longitudinal channel 186 having an open proximal end between the cam members 170 a, 170 b. The bridge 184 also includes a cross member 188 at the distal end of the channel 186. The channel 186 is dimensioned to slidably receive the engagement member 166 formed on the distal end of the nose 164 of the clamp member 118 as discussed in further detail below.

Referring to FIGS. 7-10, when the surgical stapling device 10 is in a pre-fired state, the clamp member 118 and the actuation sled 120 are in a nested configuration. In the nested configuration, the nose 164 of the clamp member 118 is positioned beneath the bridge 184 of the actuation sled 120 and the vertical strut 144 is positioned within a proximal portion of the channel 186 of the actuation sled 120 such that the engagement member 166 is positioned distally of the cross member 188 of the actuation sled 120. In addition, the upper beam 146 (FIG. 9) of the clamp member 118 is positioned proximally of the abutment surface 128 and the channel 160 of the anvil assembly 102. In this position, the sled 120 is positioned atop the lance 114 a (FIG. 4) of the support plate 114 to urge the lance 114 a out of a path of movement of the actuation sled 120.

Referring to FIGS. 9 and 10, the drive screw 116 extends through the threaded bore 150 of the clamp member 118 and includes a proximal portion that is coupled to a drive member 190 supported within the elongate body 114. The proximal portion of the drive screw 116 is supported on a bearing 192 that is configured to rotatably support the drive screw 116 as is known in the art. U.S. Pat. No. 8,512,359, hereby incorporated by reference herein, discloses a surgical stapling device including a drive screw 116 and drive member 190

Referring to FIGS. 11 and 12, when the drive screw 116 is actuated via the handle assembly 12 and the elongate body 14 to advance the clamp member 118 through a clamping stroke of the surgical stapling device 10, the clamp member moves from a retracted position to a clamped position. As the clamp member 118 moves towards the clamped position, the clamp member 118 moves independently of the actuation sled 120 along the drive screw 116 distally through the longitudinal channel 186 of the bridge 184 of the actuation sled 120. As the clamp member 118 moves distally within the proximal portion of the tool assembly 100, the upper beam 146 engages the abutment surface 128 of the anvil assembly 102 such that continued distal movement of the clamp member 118 in the direction indicated by arrow “A” in FIG. 12 to the clamped position pivots the anvil assembly 102 in the direction indicated by arrow “B” in FIG. 11 to urge the tool assembly 100 from the open position (FIG. 9) to the approximated position (FIG. 11). It is envisioned that the anvil assembly 102 may be stationary and the cartridge assembly 104 may pivot from the open position to the approximated position in relation to the anvil assembly 102.

In the clamped position, the vertical strut 144 of the clamp member 118 is positioned immediately proximal of the cross member 188 of the bridge 184 of the actuation sled 120 in the distal portion of the channel 186 and the tool assembly 100 is in the approximated position with the tissue contact surface 124 of the cartridge assembly 106 positioned in juxtaposed alignment with the tissue contact surface 102 a of the anvil assembly 102. In addition, the sled 120 remains atop the lance 114 a of the support plate 114.

In order to eject staples from the tool assembly 100, the drive member 116 is actuated again via the handle assembly 12 and the elongate body 14 to move the clamp member 118 through a firing stroke. During the firing stroke, the clamp member 118 and the actuation sled 120 are moved through a first advancement stage shown in FIG. 13, through a retraction stage shown in FIGS. 14 and 15, and through a second advancement stage shown in FIG. 16. Each of these stages is described below.

Referring to FIG. 13, during the first advancement stage of the firing stroke, the drive screw 116 advances the clamp member 118 in the direction indicated by arrow “A” distally from the clamped position. Since the vertical strut 144 is positioned adjacent the cross member 188, distal movement of the clamp member 118 causes the vertical strut 144 to engage a proximal end of the actuation sled 120 to advance the actuation sled 120 distally through the tool assembly 100. When the actuation sled 120 is advanced past the lance 114 a, the lance 114 a flexes upwardly into the path of the actuation sled 120 the first advancement stage ends.

Referring to FIG. 14, during the retraction stage of the firing stroke, the drive screw 116 is rotated in an opposite direction to retract the clamp member 118 in the direction indicated by arrows “B” within the tool assembly 100. The lance 114 a prevents proximal movement of the actuation sled 120 such that the clamp member 118 moves proximally independently of the actuation sled 118. As the clamp member 118 moves proximally, the nose 164 of the clamp member 118 slides under the bridge 184 until the proximal ramped surface 166 a of the engagement member 166 engages the cross member 188 of the bridge 184. When this occurs, continued proximal movement of the engagement member 166 of the clamp member 118 causes the cross member 188 to ride up the proximal ramped surface 166 a of the engagement member 166 into a cutout 200 in the staple cartridge 106. This allows the engagement member 166 of the clamp member 118 to move beneath the cross member 188 of the bridge 184 of the actuation member 120. By moving the clamp member 118 further proximally of the actuation sled 120, the tool assembly 100 is configured to staple tissue prior to cutting of tissue.

Referring to FIG. 15, after the retraction stage of the firing stroke, the distal surface 166 b of the engagement member 166 of the clamp member 118 is positioned adjacent to a proximal side of the cross member 188 of the actuation sled 120 and the knife 152 of the clamp member 118 is positioned proximally of the proximal end of the cam surfaces 174, 176 of the actuation sled 120. As discussed above, this ensures that tissue is stapled prior to being cut.

Referring to FIG. 16, during the second advancement stage of the firing stroke, the drive screw 116 is rotated to advance the clamp member 118 distally in the direction indicated by arrow “C” through the tool assembly 100. Since the distal surface 166 b of the engagement member 166 of the clamp member 118 is positioned adjacent to the proximal side of the cross member 188, distal movement of the clamp member 118 effects distal movement of the actuation sled 120 within the tool assembly 100. As the actuation sled 120 and the clamp member 118 are advanced through the tool assembly 100, the cam members 170 a, 170 b of the actuation sled 120 sequentially engage the pushers 110 to sequentially drive the staples 108 from the staple retention slots 124 a.

FIGS. 17 and 18 illustrate an alternate embodiment of the presently disclosed clamp member 218 and actuation sled 220. The clamp member 218 includes a base 242, a vertical strut 244, an upper beam 246, and a lower beam 248. The vertical strut 244 has a first end secured to the base 242 and a second end secured to the upper beam 246. In embodiments, the base 142 defines a threaded bore 250 that rotatably receives a drive screw 116 (FIG. 3). As discussed above, the drive screw 116 is threaded and is rotatable within the threaded bore 250 of the clamp member 218 to translate the rotational movement of the drive screw 116 into longitudinal movement of the clamp member 218.

The vertical strut 244 of the clamp member 218 includes a distal surface that defines a knife 252 that is positioned between the upper and lower beams 246, 248. The upper beam 246 is positioned to engage an abutment surface 228 (FIG. 19) of the anvil assembly 202 such that movement of the clamp member 218 from a retracted position to a clamped position (FIG. 19) moves the tool assembly 200 from the open position to the approximated position (FIG. 19). As discussed above in regard to the tool assembly 100, the upper beam 246 of the tool assembly 200 (FIG. 19) is also positioned to translate through a channel (not shown) defined in the anvil assembly 202 (FIG. 19) and the lower beam 248 is positioned to translate along the bottom surface 212 a of the cartridge channel 212 to define a maximum tissue gap between tissue contact surfaces (not shown) of the anvil assembly 202 and the staple cartridge 206.

The clamp member 218 also includes radial extensions 264 that extend outwardly from opposite sidewalls of the base 242. The radial extensions 264 each include a proximal ramped surface 266 a and a distal surface 266 b that is configured to engage and advance the actuation sled 220 as described in further detail below.

Referring also to FIG. 19, the actuation sled 220 includes a pair of spaced cam members 270 a, 270 b that are substantially similar to the spaced cam members 170 a, 170 b described above in regard to the actuation sled 120 and will not be described in further detail herein. The cam members 270 a, 270 b define a channel 271 having an open proximal end and a distal cross member 288. Each cam member 270 a, 270 b is positioned to translate through a respective longitudinal cam slot (not shown) of the staple cartridge 206 and interact with the pushers (not shown) to eject staples from the staple cartridge 206 as is known in the art. As shown, the actuation sled 220 defines a recess 284 having a distal end wall 284 a that is perpendicular to a longitudinal axis of the tool assembly 200 and a proximal end wall 284 b that defines an acute angle with the longitudinal axis of the tool assembly 200. The recess 284 is dimensioned and configured to receive the radial extensions 264 of the clamp member 218.

Referring briefly to FIG. 22, the tool assembly 200 includes a support plate 214 that is similar to support plate 114 as described above in regard to tool assembly 100. The support plate 214 differs from support plate 114 in that the support plate 214 includes at least one inwardly extending resilient tab 214 a instead of the lance 114 a (FIG. 4). Although only one tab 214 a is shown, the support plate 214 a can include a tab 214 a on each side of the support plate 214. The tabs 214 a function in a manner similar to the lance 114 a (FIG. 4) in that they provide a stop surface to prevent proximal movement of the actuation sled 220 within the support plate 214. When the actuation sled 220 is in its retracted position (FIGS. 19 and 20), a side of the sled 220 is positioned to urge the resilient tabs 214 a inwardly out of a path of movement of the actuation sled 220.

Referring to FIG. 19, prior to actuating the tool assembly 200, the clamp member 218 (shown in phantom) and the actuation sled 220 are in a nested relationship in a proximal portion of the tool assembly 200 with the vertical strut 244 of the clamp member 218 positioned in the channel 271 of the actuation sled 220 and the radial extensions 264 of the clamp member 218 positioned adjacent the proximal wall 284 b defining recess 284. As discussed above, in the retracted position of the actuation sled 220, the resilient tabs 214 a of the support plate 214 engage sidewalls of the support plate 214 and are urged out of the path of movement of the actuation sled 220.

When the drive screw 116 (FIG. 3) is actuated via the handle assembly 12 (FIG. 1) and the elongate body 14 (FIG. 1) to advance the clamp member 218 through a clamping stroke of the surgical stapling device 10, the clamp member 218 moves distally within the tool assembly 200 from its retracted position (shown in phantom) to a clamped position. As the clamp member 218 moves towards the clamped position in the direction indicated by arrow “D”, the vertical strut 244 of the clamp member 218 are advanced within the channel 271 of the actuation sled 220 and the radial extensions 264 of the clamp member 218 are advanced through the recess 284 of the actuation sled 220 such that the clamp member 218 moves independently of the actuation sled 220 along the drive screw 116. As the clamp member 218 moves towards the clamped position, the upper beam 246 of the clamp member 218 engages the abutment surface 228 of the anvil assembly 202 to pivot the anvil assembly 202 in the direction indicated by arrow “E” to the approximated position. When the clamp member 218 is in the clamped position, the radial extensions 264 of the clamp member 218 are positioned in the distal end of the recess 284 of the actuation sled 220 adjacent the distal end wall 284 a defining the recess 284. The actuation sled 220 remains in its fully retracted position.

In order to eject staples from the tool assembly 200, the drive member 116 (FIG. 3) is actuated again via the handle assembly 12 and the elongate body 14 to move the clamp member 218 through a firing stroke. During the firing stroke, the clamp member 218 and the actuation sled 220 are moved through a first advancement stage shown in FIGS. 19 and 20, through a retraction stage shown in FIG. 21, and through a second advancement stage shown in FIG. 23. Each of these stages is described below.

Referring to FIG. 20, during the first advancement stage of the firing stroke, the drive screw 116 advances the clamp member 218 in the direction indicated by arrow “F” distally from the clamped position. In the clamped position, the vertical strut 244 of the clamp member 218 is positioned in a distal end of the channel 271 of the actuation sled 220 adjacent the cross member 288 and the radial extensions 264 on the clamp member 218 are positioned adjacent the distal end wall 284 a defining the recess 284 in the actuation sled 220. As such, when the clamp member 218 is advanced along the drive screw 116 (FIG. 3), the vertical strut 244 of the clamp member 218 engages the cross member 288 (FIG. 17) and the radial extensions 264 engage the distal end wall 284 a defining the recess 284 and push the actuation sled 220 distally within the tool assembly 200. When the actuation sled 220 is advanced past the resilient tabs 214 a (FIG. 22), the tabs 214 a flex inwardly into the path of movement of the actuation sled 220 to prevent proximal movement of the actuation sled 220. At this point, the first advancement stage ends.

Referring to FIGS. 21 and 22, during the retraction stage of the firing stroke, the drive screw 116 is rotated in an opposite direction to retract the clamp member 218 in the direction indicated by arrow “G” within the tool assembly 100. The tabs 214 a prevent proximal movement of the actuation sled 220 such that the clamp member 118 moves proximally independently of the actuation sled 218. As the clamp member 218 moves proximally within the tool assembly 200, the radial extensions 264 slide within the recess 284 of the actuation sled 220 until the proximal ramped surfaces 266 a of the radial extensions 264 engage the proximal end wall 284 b defining the recess 284. When the proximal ramped surfaces 266 a of the radial extensions 264 engage the proximal end wall 284 b defining the recess 284, the actuation sled 220, which is engaged with the tabs 214 a (FIG. 22) and cannot move proximally, is cammed upwardly in the direction indicated by arrow “H” in FIG. 21, to allow the radial extensions 264 to exit the recess 284 and move to a position proximally of the actuation sled 220 (FIG. 23). By moving the clamp member 218 further proximally of the actuation sled 220, the tool assembly 200 is configured to staple tissue prior to cutting tissue.

After the retraction stage of the firing stroke, the distal surface 266 b of the radial extensions 264 of the clamp member 218 is positioned adjacent to a proximal side of the actuation sled 220 and the knife 252 (FIG. 18) of the clamp member 218 is positioned proximally of the proximal end of the cam members 270 a, 270 b of the actuation sled 220. As discussed above, this ensures that tissue is stapled prior to being cut.

Referring to FIG. 23, during the second advancement stage of the firing stroke, the drive screw 116 is rotated to advance the clamp member 218 distally in the direction indicated by arrow “I” through the tool assembly 200. Since the distal surface 266 b of the radial extensions 264 of the clamp member 218 are positioned adjacent to the proximal side of the actuation sled 220, distal movement of the clamp member 118 effects distal movement of the actuation sled 220 within the tool assembly 200. As the actuation sled 220 and the clamp member 218 are advanced through the tool assembly 200, the cam members 270 a, 270 b (FIG. 18) of the actuation sled 220 sequentially engage the pushers 110 (FIG. 3) to sequentially drive the staples 108 from the staple retention slots 124 a.

Persons skilled in the art will understand that the devices and methods specifically described herein and illustrated in the accompanying drawings are non-limiting exemplary embodiments. It is envisioned that the elements and features illustrated or described in connection with one exemplary embodiment may be combined with the elements and features of another without departing from the scope of the present disclosure. As well, one skilled in the art will appreciate further features and advantages of the disclosure based on the above-described embodiments. Accordingly, the disclosure is not to be limited by what has been particularly shown and described, except as indicated by the appended claims. 

What is claimed is:
 1. A surgical stapling device comprising: an elongate body; and a tool assembly supported on a distal portion of the elongate body, the tool assembly including a cartridge assembly and an anvil assembly, the cartridge and anvil assemblies being movable in relation to each other between spaced and approximated positions, the cartridge assembly including a staple cartridge supporting a plurality of staples, a clamp member having a body supporting a knife, an actuation sled including a cam member, and a drive member engaged with the clamp member, the drive member being movable to move the clamp member in relation to the staple cartridge between retracted and advanced positions, wherein in a pre-actuated state, the clamp member and the actuation sled are positioned in a nested relationship in which the knife of the clamp member is positioned distally of a proximal end of the cam member of the actuation sled, wherein during at least a portion of a firing stroke of the surgical stapling device, the clamp member is movable independently of the actuation sled to position the knife proximally of the cam member.
 2. The surgical stapling device of claim 1, wherein the cam member of the actuation sled includes first and second cam members interconnected by a bridge, the bridge defining a channel having an open proximal end.
 3. The surgical stapling device of claim 2, wherein the clamp member includes a vertical strut, an upper beam, and a lower beam, and in the pre-actuated state, the vertical strut is positioned within a proximal portion of the channel.
 4. The surgical stapling device of claim 3, wherein the clamp member includes a nose and the bridge includes a cross member extending across a distal end of the channel.
 5. The surgical stapling device of claim 4, wherein the nose includes an engagement member, the engagement member being positioned distally of the cross member in the pre-actuated state.
 6. The surgical stapling device of claim 5, wherein during the firing stroke, the engagement member is moved to a position proximal of the cross member.
 7. The surgical stapling device of claim 6, wherein the engagement member includes a proximal ramped surface configured to pass under the cross member of the bridge and into the channel.
 8. The surgical stapling device of claim 7, wherein the engagement member includes a distal surface configured to engage the cross-member to translate distal movement of the clamp member to distal movement of the actuation sled when the engagement member is positioned proximally of the cross member.
 9. The surgical stapling device of claim 1, wherein the clamp member includes at least one radial extension and the actuation sled defines a recess, wherein the at least one radial extension is positioned within the recess in the pre-actuated state.
 10. The surgical stapling device of claim 9, wherein the at least one radial extension is positioned in a proximal portion of the recess in the pre-actuated state.
 11. The surgical stapling device of claim 10, wherein the cam member of the actuation sled includes first and second cam members interconnected by a bridge, first and second cam members defining a channel having an open proximal end and a cross-member at a distal end of the channel.
 12. The surgical stapling device of claim 11, wherein the clamp member includes a vertical strut, an upper beam, and a lower beam, and in the pre-actuated state, the vertical strut is positioned within a proximal portion of the channel.
 13. The surgical stapling device of claim 12, wherein during a clamping stroke of the clamp member, the clamp member moves independently of the actuation sled such that the at least one radial extension moves from a proximal portion of the recess to a distal portion of the recess.
 14. The surgical stapling device of claim 13, wherein during the firing stroke, the at least one radial extension is moved from a position within the recess to a position proximal of the actuation sled.
 15. The surgical stapling device of claim 14, wherein the recess is defined by an angled proximal end wall.
 16. The surgical stapling device of claim 15, wherein the at least one radial extension has a proximal ramped surface.
 17. The surgical stapling device of claim 16, wherein the at least one radial extension includes two radial extensions positioned on opposite sides of the clamp member.
 18. The surgical stapling device of claim 1, wherein the drive member includes a drive screw. 